Apparently there's a networkstate value which will indicate 4 when a file is not found. How can I have it automatically read that value using vbscript/ASP(without the need for button click) and then submit a form or take another action? If it requires interaction, it's useless to me.

you should be able to handle this in javascript with an onerror event

Tried, but it didn't work.

can you post your code

No, it belongs to the government. Can't publish it. Was just hoping for an example written using vbscript/javascript that I could modify and integrate. The ones I've seen on the web and tried all either do nothing (e.g., onerror) or require user interaction (for which I could simply use a "report error" button).